Internal Medicine

0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:40

814 Immune Hemolytic Anemia

■CAHA

■peripheral smear may demonstrate red blood cell agglutination

■DAT positive for complement, negative for IgG; Donath-Landsteiner

test negative

■autoantibodies are most commonly IgM; rare examples of IgG and

IgA cold-reactive autoantibodies

■cold agglutinin titers > 1:1000; high thermal range reacting at 30oC

or above

■autoantibody specificity against oligosaccharide red blood cell anti-

gens of the I/i antigen system;

■polyclonal anti-I following Mycoplasma pneumoniae infection;

polyclonal anti-i following infectious mononucleosis; monoclonal

anti-I (IgM) in chronic CAHA

■PCH

■DAT infrequently positive for complement, negative for IgG; Donath-

Landsteiner test positive

■non-agglutinating, complement-fixing IgG autoantibody (Donath-

Landsteiner antibody); specificity against the P blood group antigen;

titer <1:64; moderate thermal range reacting at <20oC

■MTHA

■DAT positive for IgG and complement; IAT positive for warm-

reactive IgG autoantibodies and cold-reactive, hemagglutinating

IgM autoantibodies

■cold-reactive autoantibody component typically has low titer (1:64)

and high thermal range reacting at 30oC or above

■DIHA

■DAT positive for IgG and/or complement; IAT positive for IgG or IgM

autoantibodies

■hapten or immune complex autoantibodies in serum or from a red

blood cell eluate react only with red blood cells pre-incubated with

suspected drug

■autoantibodies formed through the “autoantibody mechanism”

react with red blood cells in the absence of the drug and are sim-

ilar to autoantibodies found in WAHA

differential diagnosis

■acute hemolytic transfusion reaction (see chapter on Transfusion

Reactions): naturally occurring anti-A and anti-B isohemagglutinins

react with transfused ABO-incompatible red blood cells, which may

lead to intravascular hemolysis, fever, nausea, vomiting, hypoten-

sion, respiratory distress, hemoglobinuria, chest/flank/infusion site

pain, acute renal failure, DIC, and death; STOP TRANSFUSION